Apparatus for and method of translating electrical variations.



P. C. HEWITT APPARATUS FOR AND METHOD OF TRANSLATING ELECTRICAL VARIATIONS.

APPLICATION FILED AUG.8. IBIS.

l,%%,492., Pitented Apr. 9, 1918.

WITNESS umren STATES PATENT orricu.

PETER COOPER HEWITT, OF RINGWOOD MANOR, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO COOPER HEWITT ELECTRIC COMPANY, OF HOBOKEN NEW JERSEY,

A CORPORATION OF NEW JERSEY.

APPARATUS FOR AND METHOD OF TRANSLATING ELECTRICAL VARIATIONS.

Specification of Letters Patent.

Patented Apr. 9, 1918.

Original application filed March 30, 1907, Serial No. 365,597. Divided and application filed May 15, 1915, Serial No. 28,433. Divided and this application filed August 8, 1916. Serial No..113,692.

' vacuum device disclosed in my prior Patent No. 1,144,596, granted June 29th, 1915, and inmy application Serial No. 28,433, filed May th, 1915, as a division thereof before said patent was issued. It involves the discovery of certain phenomena developed by the flow of electric current through a gas or vapor, and it particularly concerns the utilization of such phenomena in connection with electrical variations of all kinds'and for various'purposes.

It is useful in connection with very rapid and very feeble electrical variations, and is particularly adapted to translate Variations of potential. When used for detecting the oscillations in the receiving circuit of a space telegraph or telephone system, the results demonstrate extreme sensitiveness, reliability and durability.

My invention contemplates the employment of one or more special or auxiliary terminals, or electrodes, in operative relation to a gas or vapor carrying current, said current being supplied to the gas independently of such auxiliary terminal or terminals.

The geometrical characteristics of the conducting vapor may be determined by the size, shape, etc., of a containing vessel and by the size and position of electrodes therein. The electrical characteristics of the gas or vapor are dependent upon the geometrical characteristics, upon the kind and purity of the gas or vapor, upon the nature and material of the electrodes, and upon the density of the vapor. .The density of'the vapor depends upon the temperature and pressure, and the initial density of a given Vapor in a hermetically sealed container, may be varied through changes of internal temperature. Normal or initial internal temperature is dependent upon the temperature of the surroundings. Changes of temperature during operation are dependent upon the ratio of heat generation to heat radiation. The internal heat generation is dependent upon the above mentioned electrical characteristics and upon the amount of current flowing in the vapor device. The heat ra diation is dependent upon the heat radiating area and the temperature of the surroundings. Hence, in the operation of a'vapor device having given geometrical and electrical characteristics of construction, the density of the vapor is controllable by regulating current flow, heat radiating area, andtemperature of the surroundings.

The reactions attending passage of current in a conducting gas or vapor may be subdivided into three definite classes; (1) reactions at and near the positive electrode or anode; (2) reactions in the gas or vapor itself; and reactions at and adjacent the negative electrode, or cathode, including reactions at the junction of the negative dark space with the vapor carrying current from the main positive electrode.

The separate phenomena of which the reactions at the positive electrode or anode are made up, are numerous, and are chiefly modified by the position, size, and physical state of the anode; and by the purity, density, and kind of gas; and also by current density in the gas. Certain of them are sensitive to magnetic action. One of the visible reactions of the positive electrode or anode, is a luminous ball or bush which is very sensitive to magnetic action and which tends to be a source of variation. At low densities it is very sensitive to magnetic action.

The reactions in the conducting vapor itself and modifications thereof, independent negative electrode when it is in its primary condition, before it has been changed to what has been termed by me its low resistance or broken down state, and another class being those which exist after the negative electrode has attained the low resistance state. It'is characteristic of the first mentioned class that onsubjecting the negative electrode'in the primary condition, to sufficient electrical stress, a certain point is reached where a leakage current may be observed under certain conditions. A modified leakage currentflowing under low stress manifest when said electrode is present in a current carrying vapor having sufiicient current density. The opposition or apparent resistance to this leakage current, is modifled by the surface area of the electrode, and by the current density in the vapor adjacent thereto, and it varies in ways peculiar to itself with the nature, purity "and the density of the vapor, and with the nature and condition of the electrode. It varies with the temperature of the negative electrode, and if this temperature be increased to incandescence, this resistance then reaches or comes near its minimum limit. After the last state of resistance in the primary condition has been reached, if the temperature of the'electrode be increased to such a point as to bring about a physical or chemical change of state of the electrode, while cur-- rent, with sufficient backing, is passing into said electrode, the reactions will change to those of the second class; namely, those attendant upon the broken downstate of resistance, and the reactions of the negative electrode will then be measured by a less drop in potential. It is often desirable that the drop over the device should be as small as possible and in such case this latter state should serve best. This broken down state of the negative electrode may be attained by various expedients' now well known in the art.

Accompanying this change are the visible phenomena of the negative flame to which I have before called attention. The visible phenomena consist of a bright spot on the negative electrode with a flame apparently hovering over this spot. The peculiar characteristic of this flame is that it tends to lie in and alongthe magnetic lines of force, rather than to be twisted or distorted by them, as is usual to current passing. It tends normally to project itself perpendicularly from the surface of the electrode. A magnet may be used to modifv or adjust the conditions at the negative electrode. The

bright spot tends to locate itself at a memecus of an irregularity on an electrode.

The flame itself is surrounded by a dark space and when the flame is in normal posi tion in a right line with the vapOr column, the top of the flame usually marks the iliary terminal of this type,

aeeaaee boundary of the dark space where it joins the luminous positive column of conducting vapor coming from the positive electrode.

The flame is very sensitive to electrical variations, and such variations may be observed when looking at it. may also be varied by a magnetic field and its reactions may be made usable in this way. When the positive electrode is arranged at comparatively short distance from the negative electrode, as for instance, when located within the dark space, there may be no luminous positive column, and the reactions at the positive are modified at certain distances from the cathode and may be rendered practically unnoticeable. The positive bush reaction may be practically eliminated by these means. The length of the vapor column is decreased so that the total voltage drop across the device is decreased, and the drop due to the positive bush may be seriously modified if not altogether elin1inated. Many of the above described reactions are modified by rapid electrical variations and are useful in connection with them.

In the practice of my invention 1 expose within the vapor device, supplied with current through main electrodes, a separate terminal or two or more terminals operatively associated with a telephone or other indicating instrument and with a source of variation to be detected.

The relative positions of such terminal and of the main electrodes are of considerable importance bccause, other things being equal, the efl'ects of the reactions at an auxseem to vary with the charge in the body of vapor, particularly in the region immediately adjacent such auxiliary terminal. The current density in the vapor varies with the total amount of current flow between the main electrodes and also with the relative position or location of the auxiliary terminal with reference to the main electrodes and the current path between said electrodes. Hence, for given conditions, the proper current density or charge of the vapor adjacent an auxiliary terminal, may be attained by adjusting or arranging the auxiliary terminal nearer to or farther from the main electrodes and the path between them, or, where the auxiliary terminal is already fixed in a suitable position, by increasing or decreasing the amount of current flowing between the main electrodes. The latter expedient will usually have the effect of changing the density and distribution of the current in the vapor and may be availed of to a certain extent.

The relation of the size of the auxiliary terminal to the current or charge carried by the vapor is important and as a rough rule, the size should be decreased when the charge in the vapor is increased to obtain approximately the similar efl ects. And, further, if

Its I reactions it is desired to vary the efiect, increase of the area of the auxiliary terminal will have an effect somewhat analogous to increase of charge or current density in the body of vapor adjacent thereto.

By increasing the main current when receiving even faint signals, the volume of the signal may be amplified in many {arrangements of this device. An auxiliary electrode, because of its position or electrical connections, may have a tendency to be a positive or a negative electrode with reference to the vapor, or, being maintained at a neutral point, as by a source of counterelectromotive force, or by a condenser which may be used as such, it may under certain conditions tend to act as either, or alternately, as both. There may be a normal current flow either to or from an auxiliary terminal, and such flow may increase internally originated disturbances. There seems to be some difierence in the phenomena caused by such tendency to normal current flow through the auxiliary electrode, according as the latter has the ability to act as a cathode to receive current from the vapor, or

as an anode to deliver current to the vapor. lVhen having the ability to act as a cathode to allow current flow into the auxiliary electrode, in many cases increase of such flow seems to directly decrease sensitiveness, and may produce disturbing indications, Whereas when tending to act as an anode, too great increase of current flow apparently tends to obscure the observable indications and may mask the same under a disproportional increase of internally produced disturbances. Such disturbances may be made to assist in detecting certain kinds of variations. Hence, when the arrangement is such that the auxiliary electrode normally tends to act as an anode with current normally tending to flow from it, its area, shape, location, and material should be such as will not give rise to intense internal disturbing variations, un less it is desired to make use of them. Desirable effects are obtained where the auxiliary electrode tends to act as an anode having a slight normal current flow from it to the vapor, the quantity of such current being perhaps of the order of one-tenth to, say two milliamperes. In such case the indications from the received energy seem to be more intense up to a point where the increasing current causes disproportionately increasing disturbing conditions. When any condition of tendency to current flow to or from the auxiliary electrode suitable for receiving signals, has been attained, as for instance, where there is a normal flow of the order of to 2 milliamperes, as indicated above, or more, from such terminal, electrical conditions thus established at the surface of the terminal may be considered for some purposes, as if still existing when a counter electromotive forcefor condenser is interposed in the circuit, although the 'nor-' mal current flow is thereby checked. For most wireless work, I preferto use a small cpndenser or a counter connected potentiom e er.

The reactions at the positive electrode are normally in an unstable state and give rise to rapld electric variations, which when heard in a telephone are rumbling, rattling, cracking sounds, and may, under certain conditions, produce clear musical notes. One means of rendering the reactions at the main positive electrode substantially stable, is to bring such main positive electrode in close proximity to the main negative electrode. In such case, the visible phenomena at the main positive electrode and the voltage drop, are modified and largely suppressed, and the attendant reactions may be so rendered practically noiseless to a telephone at an auxiliary electrode.

The size of the positive electrode is important with reference to the heating effect on it and also with respect to the bush reaction. According to my invention herein clalmed, it is designed to be highly heated and its temperature may be made to affect the reactions at the negative electrode, as Well as its own.

The vapor column, considered by itself, rarely presents any source of irregular or detrimental electrical variation. It is desirable to use means to maintain the current n the vapor normally constant and uniform. in quantity and in distribution.

With a ring positive electrode, it is usually desirable-to have the lines of force some Where about 45 degrees from the normal direction of the negative electrode flame and with a disk positive electrode approximately parallel With such direction.

In all forms shown herein the conducting gas or vapor is inclosed in a suitable container preferably having three or more electrodes. The electrical reactions at the various electrodes and in the conducting medium may be thus caused and controlled as desired, to enable the development of suitable reactions within the medium itself for the desired purposes and to make possible the modification and control of the reactions. The temperature and density of the gas or vapor may be controlled in any desired way, as by determining the area and disposition of the outer radiating surfaces of the container or by the use of suitable expedients for increasing or decreasing the heat ab sorbing or heat imparting power of the surroundings, such as jacketing or immersing in heating or cooling baths parts or all of the device.

In all of the forms shown herein, the con ducting medium is referred to as a gas or vapor medium contained between electrodes "of the reactions.

in a hermetically sealed vessel, but similar circuit connections may be made serviceable the same while subjected to the action of heat and of the electric current, are now well known in the art.

While my above described invention contemplates the utilization of reactions developed by current flow in a circuit which 1n-- cludes a gas or vapor as oneof the conducting media, it will be understood that the special or auxiliary terminal and the c1rcu1t arrangements may be employed in connection with other conducting media carrying current supplied to the medium independently of the auxiliary terminal. In general the circuits whose reactions are to be utilized, should include differently conducting media afiording variable electrical reactions of various classes, such as transition resistances, etc. ll prefer a true conductor of the first class, such as ordinary conducting metals, and also aconductor of another class of conductivity as, for instance, one which is adapted to pass current after the manner of electrolytes or conducting fluids such as gases or vapors. A suitable source of electromotive force should be employed to maintain normal current flow in the circuit of the fluid medium, said current flow being preferably of relatively large quantity and low voltage. The indicator circuit should be lateral or branch or parallel circuit including a part only of the fluid medium of said'first men-- tioned circuit.

The source of variations to be translated may be a circuit of either forced variations or oscillatory variations and may be an open circuit, connected to ground or a capacity, or not, as desired. A closed'circuit of either forced variations or oscillatory variations may be applied to advantage or any-other arrangements shown in each and all of the,

figures of the drawings by connecting the two sides of such closed circuit in the same way that the aerials Sand ground G re- Spectively are connected, or in any other desired way, all as will be well understood by those skilled in the art.

I have specifically shown and described herein only a few of the typical and desirable ways of arranging the serial, indicating and direct current supply circuits. From my said Patent No. 1,144,596, it will be evident to one skilled in the art that my vapor device is so sensitive that the variations-to be detected or translated can hardly be a plied to the same in such manner as not to produce some efi'ect on the internal reactions and that those reactions will produce more or less pronounced sensible efiects in theindicator whenever the latter is applied to the vapor device in such manner that impulses, direct currents, or displacement currents may flow therethrough in response to potential variations. The instrument should he designed or located so as not to be injured by the amperage of such current flow, and, in general, it is preferableto arrange the in dicator and variation circuits in such man-- nor that the variations to .be detected may pass to the vapor device without being impeded or choked out by the indicator.

The means for starting and maintaining current flow between the main electrodes of the vapor device may be any of those com monly known in the art as suitable or desirable for' such purpose.

In my said Patent No. 1,144,596, T have shown various forms of vapor devices sup-= plied with one or more auxiliary electrodes connected with an indicating instrument in various ways. The variety ofarrangement disclosed is such as will enable those skilled in the art to understand the nature of my discovery and to arrange modifications adapting the same to further uses.

In the drawings: Figure 1 illustrates a special form of the device wherein the positive electrode is adapted to heat a projection from the mega tive electrode, certain typical circuit conlitl5 rent source, indicated in the drawings as a storage battery. This supply circuit is provided with suitable regulating devices, including preferably an adjustable ohmic re sistance and an inductance which is also preferably adjustable. The ohmic resistance and the inductance may be more or less embodied in the same device, but are preferably separate. Suitable receiving and ciated with the auxiliary electrode.

Like parts have been indicated by like reference characters on the figures wherever this is possible without liability to cause confusion.

Referring more particularly to Fig. 1,

the positive electrode 11'" maybe of any indicating circuits are operatively asso" are known or desired material suitable for the purpose, such as iron, platinum, carbon. or other conducting material;

The negative electrode 2 consists of a body or conducting liquid preferably of mercury. The auxiliary electrode 13 is preferably a solid conductor of iron, platinum, carbon, or other suitable material. The container is preferably of glass, preferably hermetically sealed, and preferably having a high vacuum when cold. It. may be of any suitable or desired size, and may be conveniently made about 2?; to 3 inches in diameter and about5 or more inches in height. A device of such diameter and 7 inches in height will have a current carrying capacity through the main electrodes up to 1 or 5 amperes at pressures of, say, 7 to 25 volts, and will have ample heat radiating area.

I arrange a projection 12 extending above the surface of the'mercury 2 and wetted thereby. A platinum wire projecting a short distance and having a diameter of .045 inch, serves well for this purpose, for currents of from 1% to 27} amperes or even more. a

A convenient method of determining or adjusting the level of the surface of the mercury consists in providing the container with a pocket 15 adapted to contain an extra supply of mercury 16. In such a device the desired amount of mercury may be poured off from the negative electrode into the pocket, or vice versa.

In the device shown in the drawings there .is a special heating action of the positive electrode 11 on the negative electrode, the positive electrode being so designed with re spect to the current flowing therethrough as to be highly heated. To this end the positive electrode is made small, so as to become heated by the passage of current from it, and is concentrically arranged around the projection 12 from the negative electrode, which it tends to heat, this projection tending to render stable and regular, the negative electrode reactions at its base. Such a positive electrode where constructed of platinum wire .057 inches in diameter and wound in a helix, having an inside diameter of 5, inch and being of two turns, will become heated with 1 ampere passing, and,

will work with 11} amperes, the bottom of the helix being substantially g inch from the level of the mercury.

The starting may be conveniently effected by shaking the device so that the mercury of the negative electrode momentarily comes in contact with the positve electrode, thereby making and breaking a bridge.

The source of current supply is shown at 8, an adjustable resistance at 9, and an adjustable inductance at 10. The supply circuit is thus capable of regulation for purposes of controlling the amperage through the lamp and for steadying the same to normallyuniform values.

The auxiliary terminal 13 is sensitive to the electrical variations to be detected and these are operatively applied to the device from any suitable source of variation, as, for instance, a receiving wire S of a space telegraph or telephone system brought in proximity to the device or connected directly to the auxiliary terminal. It will be understood that the variations to be utilized, may be from other sources and may be of comparativelv low frequency and greater amperage. he detecting circuit is preferably arranged to have a suitable value of impedance, that furnished by a telephone receiver serves well, and a telephone having a resistance of 500 to 2000 ohms is frequently found suitable for the purpose of wireless telegraphy. In case the impedance is the primary of a transformer, the inductance and resistance may be selected to suit, as desired.

The electromotive force across the indicator circuit from the auxiliary terminal to the main negative electrode is more or less counter-balanced, or if desired, over-bah anced by the potentiometer 18 shown. The

.latter may be adjusted to cause slight current flow to or from the auxiliary electrode.

In Fig. 2 the vapor device is shown with connections to a receiving circuit which may be useful with other forms of the device. The receiving conductor S is shown tuned as at 47 to a quarter wave length and the lateral conductor 45 leading to the electrode 13 of the vapor device is also tuned as at 4:6 to the same frequency. The ground connection G may be adjustable as at 48 and when the latter is used the circuit G, 48, 4:7, S will be the electrical equivalent of the circuit G, 48, 46, 45, 13", so that there will be a crest of potential at 13.

The circular auxiliary electrode 13 is shown in Fig. 2 as flattened and arranged in a transverse plane with the flat surface approximately equidistant from the path between the main electrodes, so that almost all of the surface of the electrode exposed to the Vapor lies in an approximately equipotential region of suitable current density. This arrangement has certain advantages where it is desired to use a fine adjustment of counter electromotive force of a potentiometer to secure the most sensitive condition for feeble signals. One reason for this is that if the auxiliary electrode is formed or arranged so that the exposed surface thereof extends through regions at materially difierent distances from the path between the main electrodes, different parts of such exposed surface may lie in regions of materially different current density. While this latter condition may not be objectionable for many purposes, it is sometimes 4 mining factor the current density in the P01? motive force may be very accurately adjust- I found to be unsatisfactory for the finest work in connection with the faintest signals.

One probable reason for this is that the condition of most extreme sensitiveness of the auxiliary electrode seems to depend upon getting an extremely fine balance of the counter-electromotive I force 'of the potentiometer against the electrical pressure at the surface of the auxiliary electrode. lhe latter pressure has for one important detertion of the vapor in contact with the electrode, and'it seems to be a fact that if the auxiliary electrode is so formed or arranged that there are materially different current densities in the vapor adjacent difierent portions of its surface, the counter-electromotive force of the potentiometer When set to a proper value for the current density adjacent one portion of the exposed surface, will be either toogreat or too small for other portions Where the adjacent current density is of difierent value. On the other hand, if all portions of the exposed electrode surface are acted upon by vapor of substantially the same current density, the counter-electroed to that current density, and such adjust- 'ment being perfect for one portion of the electrode is perfect for any other portion of the electrode.

, Another reason may be that a uniform density of current flow into and out of a considerable area of the electrode may be desirable. This result should be accomplished by the above arrangement of the auxiliary electrode, because by it the lengths and resistances of the vapor path from different portions of the surface of the elec-' teristics may be relied upon for the rectification or asymmetric translationof variations of an extremely small fraction of a volt and of the highest frequency, thereby rendering possible the use of a direct current indicating instrument.

I have found it desirable in order to fully utilize the asymmetric resistance characteristics of the device to so arrange the auxil iary electrode that it will act as an approxi- ,mately no resistance positive electrode and as a substantially prohibitive negative electrode with respect to oscillations, (of the aaeaaea strength which it is desired to translate or detect by such device. When properly deslgned and arranged, the half waves or impulses coming throngh such electrode pass ofi freely into the gas or vapor, but the half Waves or impulses tending to run in the opposite direction are substantially blocked, thus giving the rectifying efi'ect necessary for operating the direct current or other instrument.

It will be understood, however; that the devgce is so remarkably sensitive in such a varlety of Ways that it will act as a very good detector of feeble variations such as are characteristic of the receiving wires of ordinary commercial Wireless telegraph systems, even when the ad'ustments are such that the asymmetric aettdn is at a minimum.

ll claim: v

1. A device for translating electrical variations comprising a hermeticallysealed contalner containing a monatomic gas, a positive electrode therein constructed and arranged so as to be kept hot by current flow therethrough and a coiiperating electrode in close proximity to but out of electrical contact with said first mentioned electrode so as to be heated thereby and means for passing current through said electrodes, in combination with an auxiliary electrode in said container and a circuit therefrom to one of said first mentioned electrodes.

2. A device for, translating electrical variations comprising a hermetically sealed contamer containing a monatomic gas, a posi- 'tive electrode therein constructed and arranged so as to be kept at luminous heat by current flow therethrough intosaid gas and a cciiperating negative electrode comprising a body of mercury and a metallic projection above the surface thereof in close proximity to said first mentioned electrode so as to be heated thereby, and means for passing current through said electrodesin combination with an auxiliary electrode in said container and a circuit therefrom to one of said first mentioned electrodes.

3. A device for translating electrical variations'comprising a hermetically sealed container, a positive electrode therein constructed and arranged so as to be kept incandescent by current flow therethrough and a coiiperating negative electrode comprising a body of mercury and a metallic projection above the surface thereof surrounded by said first mentioned electrode so asto be heated thereby, and a source of electromotive force for passingcurrent through said electrodes, in combination with an auxiliary electrode and a circuit therefrom to one of said first mentioned electrodes.

4. A device for translating electrical variations comprising a hermetically sealed container, a positive electrode therein constructed and arranged so as to be kept hot by current flow therethrough and a cooperating electrode adapted to dissipate heat, arranged in close proximity to but out of electrical contact with said positive electrode so as to be heated thereby, and a source of electromotive force for passing current through said electrodes, in combination with an auxiliary electrode and a circuit there from to one of said first mentioned electrodes.

5. A device for translating electrical variations comprising an exhausted hermetically sealed container, a positive electrode therein constructed and arranged so as to be kept hot by current flow, a cooperating electrode in close proximityto but out of electrical contact with said first mentioned electrode, and means for passing current through said electrodes, in combination with an auxiliary electrode in said container and a circuit therefrom to one of said first mentioned electrodes.

6. A device for translating electrical variations comprising an exhausted hermetically sealed container, a positive electrode therein constructed and arranged so as to be kept at luminous heat by current flow therethrough into said gas and a cooperating negative electrode comprising a body of mercury and a metallic projectionabove the surface thereof in close proximity to said first mentioned electrode, and means for "passing current through said electrodes in combination with an auxiliary electrode Within said container, and a clrcuit thereconstructed and arranged so as to be kept incandescent by current flow therethrough and a cooperating negative electrode comprising a metallic projection, surrounded by said first mentioned electrode, and a source of electromotive force for passing current through said electrodes in combination With an auxiliary electrode Within said container, and a circuit therefrom through said container. A

8. A device for translating electrical variations comprising an exhausted hermetically sealed container, a positive electrode therein constructed and arranged so as to be kept hot by current flow therethrough and a cooperating electrode adapted to dissipate heat, arranged in heat receiving proximity to but out of electrical contact with said positive electrode so as to be heated thereby, a source of electromotive force for passing current through said electrodes, an auxiliary electrode and a circuit therefrom to one of said first mentioned electrodes.

Signed at New York city, in the county of New York and State of New York this 27th day of July, 1916.

PETER COOPER HEWITT.

\Vitnesses:

VVALTER R. F. BRADLEY, JOHN F. NELSON. 

